Michael Kasha

Distinguished University Research Professor
Ph.D. (1945) University of California, Berkeley
Member of the National Academy of Sciences

Department of Chemistry and
Institute of Molecular Biophysics           Tel:(850)644-1519       
Florida State University                    kasha@sb.fsu.edu
Tallahassee, FL 32306-3015

Dr. Kasha is one of the original founders of the Institute of Molecular Biophysics.


Molecular spectoscopy research defining new excitation mechanisms with applications to biophysical phenomena.
The research in this molecular spectroscopy laboratory has maintained a strong tradition of the discovery and elucidation of excitation mechanisms, with particular application to photochemical and biophysical problems.

Currently there are three general themes in our research:

New types of fluorescence probes. Some molecular structural types have been demonstrated to exhibit two or three competing fluorescences: normal, charge-transfer, and proton-transfer fluorescences. Each of these has individual sensitivities to environments, including polarity, polarizability, and restriction of intramolecular motion. Consequently, they act as discrimi-nating probes, and offer relaxation dynamical characterization as well as static environmental characterization of solvents, protein binding sites, zeolites, cyclodextrins, and other solvent cages.

Photon-antenna, energy-trap model. We have developed a theory coupling the Davydov exciton model with the Förster resonance transfer model, offering ultra-long-range coupling of molecular excitation. This extends our previous work on the underlying mechanism of excitation transfer in the photosynthetic reaction center (the `special pair' chlorophyll model utilizes the McRae-Kasha dimer selection rules), to other amplification mechanisms for localized probe excitation.

Solvent cage theory. We have published a quantum mechanical theory of the solvent cage model. The idea in kinetics format was originated by Franck and Rabinowitsch. Our quantum mechanical theory predicts specific treatment of spectroscopic phenomena, and a number of new phenomena have been predicted and observed. To date, the theory has been limited to mechanical solvent cage effects on intramolecular motion. Our new direction is to investigate the effect of dielectric cages on solute molecules under excitation. Again, new phenomena are foreseen, which will offer understanding of polar environments, and their relaxation effects.


SELECTED PUBLICATIONS

Kasha, M., Sytnik, A. And Dellinger, B., "Solvent Cage Spectroscopy," Pure and Appl. Chem., 65, 1641-1646, 1993.

Sytnik, A. and Kasha, M., "Excited-State Intramolecular Proton Transfer as a Fluorescence Probe for Protein Binding-site Static Polarity," Proc. Natl. Acad. Sci. USA, 91, 8627-8630, 1994.

Sytnik, D., Gormin, D. And Kasha, M., "Interplay Between Excited-State Intramolecular Proton Transfer and Charge Transfer in Flavonols and Their Use as Protein-Binding-Site Fluorescence Probes," Proc. Natl. Acad. Sci. USA, 91, 11968-11972, 1994.

Khan, A. U. And Kasha, M., "Singlet Molecular Oxygen Evolution upon Simple Acidification of Aqueous Hypochlorite: Application to Studies on the Deleterious Health Effects of Chlorinated Drinking Water," Proc. Natl. Acad. Sci. USA, 91, 12362-12364, 1994.

Khan, A. U. And Kasha, M., "Singlet Molecular Oxygen in the Haber-Weiss Reaction," Proc. Natl. Acad. Sci. USA, 91, 12365-12367, 1994.

Gormin, D., Heldt, J. And Kasha, M., "Triplet State Potentials in the Competitive Excitation Mechanisms of Intramolecular Proton Transfer," J. Phys. Chem., 99, 7281-7284, 1995.

Gormin, D., Sytnik, A. and Kasha, M., "Spectroscopy of Amplified Spontaneous Emission Spectroscopy (ASE) Laser Spikes in Polyhydroxylflavones. Protoype Classes," J. Phys. Chem. A, 101, 3260-3272, 1996.

del Valle, J.-C., Kasha, M. and Catalán, J., "Chemical Physics of Excitation Dynamics via Amplified Spontaneous Emission (ASE) Laser Spike Spectroscopy in Substituted Phenyloxazoles," Chem. Phys. Lett. (in press, July 1996).